Mechanical responses of the isolated cervix of the day-22 pregnant rat to field stimulation

Summary Field stimulation of isolated, spirally-cut cervix from day-22 pregnant rats produced contractions which could be inhibited by tetrodotoxin or hyoscine and potentiated by propranolol. The rat cervix would appear to receive both cholinergic and noradrenergic innervations whose transmitters activate muscarinic cholinoceptors and -adrenoceptors respectively.We thank the Lalor Foundation, USA, for financial support.     

Supernormal responses to premature stimulation in Ca-dependent action potentials.

The responses of Ca-dependent action potentials to premature stimulation were studied in the isolated canine ventricular muscle. When very premature stimuli were applied, supernormally augmented responses with propagation occurred, while responses with long preceding intervals were small and not conducted.     

EMG responses to capsular stimulation in the human

Riassunto Gli autori studiano la latenza e le caratteristiche elettromiografiche delle risposte muscolari provocate con stimoli capsulari nell'uomo. Le clonie provocate in muscoli in stato di leggera contrazione sono seguite in genere da una fase di rilasciamento muscolare di 50–200 msec di durata.     

Physiologic and pharmacologic responses of mammalian vascular smooth muscles during electric field stimulation

Résumé Des sections de muscle lisse d'aorte de lapin ou d'artère fémorale de chien répondent à une stimulation de champ (AC) par une contraction due en partie à la libération de catécholamines, contraction pouvant être relâchée sous l'effet de divers médicaments. D'autre part, l'AC manifeste une action au niveau de la membrane excitable et au-delà de cette membrane. Il en a peut-être aussi sur le couplage excitation-contraction. L'AC offre une méthode unique pour l'étude des agents susceptibles d'avoir une action vaso-dilatatrice.     

Differential effects of calcium channel blockers on the responses of the rat vas deferens to intramural nerve stimulation and exogenous drugs

The calcium channel blockers, nifedipine and verapamil, have separate effects on the phases of nerve-induced twitches which are not reflected by their actions on the responses to exogenous NA, ATP and the stable ATP analogue, alpha, beta-mATP. This implies that different calcium channels are used according to the manner of stimulation.     

Differential effects of calcium channel blockers on the responses of the rat vas deferens to intramural nerve stimulation and exogenous drugs

Summary The calcium channel blockers, nifedipine and verapamil, have separate effects on the phases of nerve-induced twitches which are not reflected by their actions on the responses to exogenous NA, ATP and the stable ATP analogue, ,-mATP. This implies that different calcium channels are used according to the manner of stimulation.     

Fatty acids of the pregnant rat uterus

Zusammenfassung Die Untersuchung über die Fettsäure-Zusammensetzung der Ratten-Uteruslipide während der Gravidität ergab ein unverändertes Verbreitungsmuster bei den Hauptfettsäuren der neutralen Lipoide.

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Supported in part by NIH grant No. HD-02599.     

Effects of temperature on the responses to noradrenaline, isoprenaline and histamine on isolated rabbit mesenteric artery.

On the rabbit mesenteric artery, the elevation of temperature from 25 degrees up to 42 degrees diminished the affinity of histamine, whereas that of noradrenaline to the alpha-adrenoceptors remained unchanged. The presence of beta-adrenoceptors could not be demonstrated.     

Release of renal kallikrein to the perfusate by isolated rat kidney

Summary The addition of furosemide to the fluid used to perfuse isolated rat kidney increases the kallikrein activity found in the perfusion fluid. The experiments favour the concept that furosemide activates a kallikrein precursor or/and the synthesis and release of kallikrein in the kidneys.     

Effects of Tabermanthe iboga H. Bn. alkaloids on the isolated organ responses to catecholamines and the role of calcium exchanges. Tabernanthine]

Using isolated Rat duodenum previously decalcified, the authors have investigated the effect of tabernanthine on the increase of tonus brought about by addition of calcium ions at different concentrations. The observed potentiating effect of tabernanthine towards the calcium responses may be pointed out concerning the mechanism of sensitizing effect of this alkaloid on the responses of isolated organs to catecholamines such as noradrenaline and dopamine.     

Effect of acetone on VLDL secretion by the isolated rat liver.

High acetone levels occur in uncontrolled diabetes and after isopropanol administration to rats. In both conditions, very low density lipoproteins (VLDL) secretion is depressed. Acetone, hoever, failed to affect the VLDL secretion rate by the isolated perfused rat liver, suggesting that this metabolite is not involved in impaired VLDL production in diabetes and after isopropanol administration.     

Effects of mescaline and lysergide on the mechanical responses of isolated organs of the rat to catecholamines and the role of calcium transfers in these phenomena]

On isolated Rat vas deferens the contracting responses of noradrenaline and dopamine are increased by mescaline (23 micromoles) and decreased by lysergide (15 micromoles). Similarly, on isolated Rat duodenum previously decalcified the hypertonic responses of recalcification are modified in the opposite direction by the two agonists. On the other hand, mescaline such as lysergide increase the fall of tonus which ensues the decalcification of isolated duodenum.